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e7ee514058
The code instantiating an i2c-mux-gpio platform device doesn't necessarily know in advance the GPIO pin numbers it wants to use. If pins are on a GPIO device which gets its base GPIO number assigned dynamically at run-time, the values can't be hard-coded. In that case, let the caller tell i2c-mux-gpio the name of the GPIO chip and the (relative) GPIO pin numbers to use. At probe time, the i2c-mux-gpio driver will look for the chip and apply the proper offset to turn relative GPIO pin numbers to absolute GPIO pin numbers. The same could be (and was so far) done on the caller's end, however doing it in i2c-mux-gpio has two benefits: * It avoids duplicating the code on every caller's side (about 30 lines of code.) * It allows for deferred probing for the muxed part of the I2C bus only. If finding the GPIO chip is the caller's responsibility, then deferred probing (if the GPIO chip isn't there yet) will not only affect the mux and the I2C bus segments behind it, but also the I2C bus trunk. Signed-off-by: Jean Delvare <khali@linux-fr.org> Cc: Peter Korsgaard <peter.korsgaard@barco.com>
44 lines
1.4 KiB
C
44 lines
1.4 KiB
C
/*
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* i2c-mux-gpio interface to platform code
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*
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* Peter Korsgaard <peter.korsgaard@barco.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#ifndef _LINUX_I2C_MUX_GPIO_H
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#define _LINUX_I2C_MUX_GPIO_H
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/* MUX has no specific idle mode */
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#define I2C_MUX_GPIO_NO_IDLE ((unsigned)-1)
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/**
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* struct i2c_mux_gpio_platform_data - Platform-dependent data for i2c-mux-gpio
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* @parent: Parent I2C bus adapter number
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* @base_nr: Base I2C bus number to number adapters from or zero for dynamic
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* @values: Array of bitmasks of GPIO settings (low/high) for each
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* position
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* @n_values: Number of multiplexer positions (busses to instantiate)
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* @classes: Optional I2C auto-detection classes
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* @gpio_chip: Optional GPIO chip name; if set, GPIO pin numbers are given
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* relative to the base GPIO number of that chip
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* @gpios: Array of GPIO numbers used to control MUX
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* @n_gpios: Number of GPIOs used to control MUX
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* @idle: Bitmask to write to MUX when idle or GPIO_I2CMUX_NO_IDLE if not used
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*/
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struct i2c_mux_gpio_platform_data {
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int parent;
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int base_nr;
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const unsigned *values;
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int n_values;
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const unsigned *classes;
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char *gpio_chip;
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const unsigned *gpios;
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int n_gpios;
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unsigned idle;
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};
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#endif /* _LINUX_I2C_MUX_GPIO_H */
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